Radiation: Function, Tasks, Role & Diseases

Thermoregulatory radiation is a mechanism of heat loss characterized by heat radiation. Radiation involves heat energy moving out of the body as electromagnetic waves or infrared radiation. Superheating by radiation is considered a therapeutic step in cancer.

What is Radiation?

Human body temperature is constantly maintained by a wide variety of mechanisms. The temperature of about 37 degrees Celsius (varies slightly from person to person) corresponds to the ideal working temperature of numerous enzymes. The human body temperature is constantly maintained by various mechanisms. The temperature of about 37 degrees Celsius (which varies slightly from person to person) corresponds to the ideal working temperature of numerous enzymes. To maintain this ideal value, the human organism is in constant heat exchange with the environment. The totality of these exchange processes and the body processes interconnected with them is called thermoregulation of the body. The hypothalamus is the regulatory center. The four mechanisms of heat exchange are convection, conduction, evaporation and radiation. Medicine distinguishes between mechanisms of external and internal heat transport. Internal heat transport occurs predominantly via convection and conduction. Conduction does not require a carrier medium, whereas convection works with a carrier medium. Radiation and evaporation are primarily attributed to external heat transport. While evaporation corresponds to evaporation, radiation is thermal radiation.

Function and task

Radiation involves the movement of heat energy in the form of an electromagnetic wave as infrared radiation. Unlike, for example, transport by convection, radiation thus does not rely on matter, but works exclusively with materialless thermal radiation. Without reflection, long-wave infrared rays penetrate the human body from the outside. These long-wave rays can emanate from various sources in the environment. The most important source of long-wave infrared radiation is, for example, the sun. However, objects or people in the immediate environment can also emit long-wave infrared radiation. Short-wave infrared rays do not enter the organism unreflected, but are reflected by up to 50 percent. This reflection takes place mainly through the skin pigment. The Stefan-Boltzmann law gives the thermal radiation power of an ideal black body as a function of body temperature. It goes back to the physicists Ludwig and Josef Stefan Boltzmann. Their law forms the basic framework of thermoregulatory radiation. The Stefan-Boltzmann law was discovered more or less experimentally in the 19th century. Boltzmann based his derivation on the laws of thermodynamics and Maxwell’s electrodynamics. In the derivation he presupposes the spectral radiance of black bodies and achieves an integration of the radiance over all frequencies and into the half-space irradiated by the surface element. Accordingly, the radiation law of the radiation indicates which radiation power a black body of a certain area with the absolute temperature emits into the environment. Heat is constantly generated in the human body, mainly by metabolic processes and muscular work. This heat is transported to the surface by internal heat transport processes such as conduction and convection. From the body surface the heat radiates in the context of the Radiation after the described law of Boltzmann, so that heat losses occur. These heat losses protect the human body from overheating. On the other hand, the human body also absorbs heat from the environment via radiation. In order to maintain a constant body temperature, heat losses are initiated again if necessary. Thus, thermoregulatory processes such as radiation, convection, evaporation, and conduction protect the human body from overheating and hypothermia. Both conditions would disrupt or even paralyze enzymatic work and thus dozens of body processes.

Diseases and ailments

Hyperthermia refers to an overheating of the body that runs against the thermoregulatory center. Unlike fever, hyperthermia is not caused by pyrogens.Hyperthermic special forms are malignant hyperthermias, which occur due to drug effects or drug consumption. Hyperthermia can also be induced artificially via radiation and then corresponds to a therapeutic step, as it is useful, for example, in the context of cancer treatments. Chemotherapies are often successfully supported by artificial hyperthermia. Different types of artificial hyperthermia are distinguished. In addition to whole-body hyperthermia, there is, for example, deep hyperthermia or prostate hyperthermia. In whole-body hyperthermia, the entire body is overheated, except for the head. This targeted overheating takes place with the help of infrared radiators and brings the body temperature to values up to 40.5 degrees Celsius. Deep hyperthermia takes place only on the affected tissue and warms the diseased part of the body up to 44 degrees Celsius. Prostate hyperthermia is usually produced by transurethral hyperthermia. In addition to heat, the radiation of an electric field of radio short waves is used. Hyperthermia as a medical term is contrasted with hypothermia. It refers to hypothermia caused by excessive heat loss via radiation, conduction, convection and evaporation. Hypothermia due to heat loss is mainly supported by low air temperature. Cold water or wind also promote heat loss from a body. Typically, hypothermia therefore occurs in the context of accidents in water, mountains, and caves. Staying in generally cold environments can also cause hypothermia. Medicine distinguishes between mild, moderate and severe hypothermia. Severe hypothermia causes the body temperature to drop below 28 degrees Celsius and can have fatal consequences. In addition to unconsciousness or circulatory arrest, this form of hypothermia is characterized by decreased brain activity, pulmonary edema and fixed pupils. Cardiac arrhythmias occur. Respiratory arrest due to hypothermia is also common.